The basement membrane synthesized by microvascular endothelial cells is thought to play an important role in the proper physiological functioning of this cell type. Preliminary evidence obtained in vitro from a number of laboratories has indicated that microvascular endothelial cells and their underlying basement membrane have an interactive relationship; changes in the molecular composition of the growth substratum induce changes in the growth, morphology, and biosynthetic capacity of the overlying cell layer. At present, however, there are no systematic studies available which detail how specific changes in the basement membrane may "feedback" and influence the associated cell layer. It is the ultimate goal of this research to determine the biological function of complex glycoconjugates in this interactive relationship. The methodology described in this proposal provides for systematic and controlled modification of the glycoconjugate structures present in basement membrane. Microvascular endothelial cells will subsequently be plated onto control or modified matrices and their capacity to synthesize three specific basement membrane components, collagen, laminin, and heparan sulfate proteoglycan, will be assessed. Any changes in the biosynthetic capacity of cells cultured on control versus modified matrices may then be attributed directly to the structural changes in the proteoglycan of glycoprotein components of extracellular matrix. it is hoped that the systematic modification experiments described in this proposal will be useful in identifying those portions of the complex glycoconjugate structure that are recognized as biologically significant by the overlying cell layer.